Struts2 Data Transfer

Can anybody tell me how to transfer list of similar kind of data to action classs in struts2?

For example, I have a student form which collects several students data at a time, so how can I populate it in action class? I want to map the fields back and forth. i.e form to action and action to form. I am able to map from action to form by iterating my student list which is populated in action, but could not do it from form to action. The form look like below. Here use can add as many students(rows) as he wants.